1. Field of the Invention
The present invention relates to a composition for film formation, a resist underlayer film, a forming method of a resist underlayer film, and a pattern-forming method.
2. Discussion of the Background
In manufacturing semiconductor devices and the like, multilayer resist processes have been employed for attaining a high degree of integration. In these processes, generally, a composition for forming a resist underlayer film is first coated on the upper face side of a substrate to form a resist underlayer film, and then a resist pattern is formed on the upper face side of the resist underlayer film. Subsequently, the resist pattern is transferred to the resist underlayer film through etching, and the resist underlayer film pattern is then transferred to the substrate, thereby enabling a desired pattern to be obtained. Resist underlayer films used in such multilayer resist processes are required to exhibit general characteristics such as optical characteristics, e.g., appropriate refractive index and extinction coefficient, as well as favorable etching resistance.
In recent years, microfabrication of patterns has been further in progress in order to further increase the degree of integration. To meet such microfabrication, structures, functional groups, etc., of compounds and the like contained in the composition for forming a resist underlayer film have been variously investigated (see Japanese Unexamined Patent Application, Publication No. 2004-177668).
Recently, methods which include providing a hard mask on a resist underlayer film using CVD techniques in the multilayer resist processes have been investigated. Specifically, in these processes, an inorganic hard mask as an intermediate layer is formed on the resist underlayer film using a CVD technique. In a case where the inorganic hard mask, particularly an inorganic nitride hard mask, is formed by using the CVD technique, a substrate needs to be heated to a temperature of at least 300° C., and typically 400° C.
Moreover, in these days, formation of a pattern on a substrate having a plurality of types of trenches, in particular, trenches differing from one another in terms of an aspect ratio has been executed more frequently. Even in the case where such a substrate is employed, the resist underlayer film is required to be formed such that these trenches are sufficiently buried, with superior flatness.